U.S. patent application number 12/273552 was filed with the patent office on 2009-12-03 for seal ring structure for integrated circuits.
Invention is credited to Tien-Chang Chang, Yuan-Hung Chung, Tung-Hsing Lee.
Application Number | 20090294929 12/273552 |
Document ID | / |
Family ID | 41378730 |
Filed Date | 2009-12-03 |
United States Patent
Application |
20090294929 |
Kind Code |
A1 |
Lee; Tung-Hsing ; et
al. |
December 3, 2009 |
SEAL RING STRUCTURE FOR INTEGRATED CIRCUITS
Abstract
A seal ring structure disposed along a periphery of an
integrated circuit. The seal ring is divided into at least a first
portion and a second portion. The second portion is positioned
facing and shielding an analog and/or RF circuit block from a
noise. A deep N well is disposed in a P substrate and is positioned
under the second portion. The deep N well reduces the substrate
noise coupling.
Inventors: |
Lee; Tung-Hsing; (Taipei
County, TW) ; Chang; Tien-Chang; (Hsinchu City,
TW) ; Chung; Yuan-Hung; (Hsinchu County, TW) |
Correspondence
Address: |
NORTH AMERICA INTELLECTUAL PROPERTY CORPORATION
P.O. BOX 506
MERRIFIELD
VA
22116
US
|
Family ID: |
41378730 |
Appl. No.: |
12/273552 |
Filed: |
November 19, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61057185 |
May 29, 2008 |
|
|
|
Current U.S.
Class: |
257/659 ;
257/E23.114 |
Current CPC
Class: |
H01L 2924/0002 20130101;
H01L 23/5225 20130101; H01L 23/585 20130101; H01L 23/552 20130101;
H01L 2924/0002 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
257/659 ;
257/E23.114 |
International
Class: |
H01L 23/552 20060101
H01L023/552 |
Claims
1. A seal ring structure for an integrated circuit, comprising: a
seal ring disposed along a periphery of the integrated circuit,
wherein the seal ring is divided into at least a first portion and
a second portion, and wherein the second portion is positioned
facing and shielding an analog and/or RF circuit block from a
noise; and a deep N well in a P substrate and positioned under the
second portion.
2. The seal ring structure according to claim 1 wherein the seal
ring is discontinuous, the second portion is spaced apart from the
first portion.
3. The seal ring structure according to claim 1 further comprising
a continuous outer seal ring outside the seal ring.
4. The seal ring structure according to claim 1 wherein a length of
the second portion is equal to or greater than a span of the
shielded analog and/or RF circuit block.
5. The seal ring structure according to claim 1 wherein the first
portion comprises a first P.sup.+ region in the P substrate.
6. The seal ring structure according to claim 1 wherein the second
portion comprises a second P.sup.+ region in the deep N well.
7. The seal ring structure according to claim 6 further comprising
a P well between the second P.sup.+ region and the deep N well.
8. The seal ring structure according to claim 6 wherein the second
portion further comprises a first N well electrically isolated from
the second P.sup.+ region by a first shallow trench isolation (STI)
structure, a second N well electrically isolated from the second
P.sup.+ region by a second STI structure.
9. The seal ring structure according to claim 8 wherein the first
and second N wells have a junction depth d.sub.1 of about
11000-15000 angstroms and the deep N well has a junction depth
d.sub.2 of about 19000-21000 angstroms.
10. The seal ring structure according to claim 8 wherein the first
N well and the second N well are coupled to the deep N well.
11. The seal ring structure according to claim 1 wherein the second
portion comprises an N.sup.+ region in the deep N well.
12. The seal ring structure according to claim 1 wherein the deep N
well is grounded or coupled to a supply voltage.
13. The seal ring structure according to claim 1 wherein the second
portion comprises a conductive rampart that is a stack comprising a
metal layer, a contact/via layer or a combination thereof and is
manufactured together with the fabrication of the integrated
circuit.
14. A seal ring structure for an integrated circuit, comprising: a
seal ring disposed along a periphery of the integrated circuit,
wherein the seal ring is divided into at least a first portion and
a second portion; a first deep N well in a P substrate and
positioned under the first portion; and a second deep N well in a P
substrate and positioned under the second portion.
15. The seal ring structure according to claim 14 wherein the seal
ring is discontinuous, the second portion is spaced apart from the
first portion.
16. The seal ring structure according to claim 14 further
comprising a continuous outer seal ring outside the seal ring.
17. The seal ring structure according to claim 14 wherein a length
of the second portion is equal to or greater than a span of an
analog and/or RF circuit block of the integrated circuit.
18. The seal ring structure according to claim 17 wherein the
second portion is positioned facing and shielding the analog and/or
RF circuit block from a noise.
19. The seal ring structure according to claim 14 wherein the first
portion comprises a first P.sup.+ region in the first deep N
well.
20. The seal ring structure according to claim 14 wherein the
second portion comprises a second P.sup.+ region in the second deep
N well.
21. The seal ring structure according to claim 20 further
comprising a P well between the second P.sup.+ region and the
second deep N well.
22. The seal ring structure according to claim 20 wherein the
second portion further comprises a first N well electrically
isolated from the second P.sup.+ region by a first shallow trench
isolation (STI) structure, a second N well electrically isolated
from the second P.sup.+ region by a second STI structure.
23. The seal ring structure according to claim 22 wherein the first
and second N wells have a junction depth d.sub.1 of about
11000-15000 angstroms and the second deep N well has a junction
depth d.sub.2 of about 19000-21000 angstroms.
24. The seal ring structure according to claim 22 wherein the first
N well and the second N well are coupled to the second deep N
well.
25. The seal ring structure according to claim 14 wherein the
second deep N well is grounded or coupled to a supply voltage.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
application No. 61/057,185, filed May 29, 2008.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention related to semiconductor devices and,
more particularly, to a seal ring structure for an integrated
circuit that is capable of reducing substrate noise coupling.
[0004] 2. Description of the Prior Art
[0005] Advances in fabrication technology have enabled entire
functional blocks, which previously had been implemented as plural
chips on a circuit board, to be integrated onto a single IC. One
particularly significant development is mixed-signal circuits,
which combine analog circuitry and digital logic circuitry onto a
single IC.
[0006] However, a major technical hurdle to implementing
mixed-signal circuits has been the coupling of noise between
different portions of the IC, for example, from the digital to the
analog portions. Ordinarily, an integrated circuit chip includes a
seal ring used to protect it from moisture degradation or ionic
contamination. Typically, the seal ring is made of a stack of metal
and contact/via layers and is manufactured step by step as
sequential depositions of insulators and metals in conjunction
together with the fabrication of the integrated circuit
elements.
[0007] It has been found that the noise, such as digital noise,
which, for example, may be originated from a digital power signal
line such as V.sub.DD or signal pad of a digital circuit,
propagates through the seal ring and adversely affects the
performance of the sensitive analog and/or RF circuit.
SUMMARY OF THE INVENTION
[0008] It is one object of the present invention to provide an
improved seal ring structure of an integrated circuit chip, which
is capable of reducing the digital noise coupling from a digital
circuit.
[0009] The above object will be achieved by the seal ring structure
in the present invention which comprises a seal ring disposed along
a periphery of the integrated circuit, wherein the seal ring is
divided into at least a first portion and a second portion, and
wherein the second portion is positioned facing and shielding an
analog and/or RF circuit block from a noise; and a deep N well in a
P substrate and positioned under the second portion.
[0010] In one aspect, the present invention provides a seal ring
structure for an integrated circuit including a seal ring disposed
along a periphery of the integrated circuit, wherein the seal ring
is divided into at least a first portion and a second portion; a
first deep N well in a P substrate and positioned under the first
portion; and a second deep N well in a P substrate and positioned
under the second portion.
[0011] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrate
embodiments of the invention and, together with the description,
serve to explain the principles of the invention. In the
drawings:
[0013] FIG. 1 is a schematic, planar view of an integrated circuit
chip with a double seal ring structure in accordance with one
preferred embodiment of this invention;
[0014] FIG. 2 is a schematic, cross-sectional view taken along line
I-I' of FIG. 1;
[0015] FIG. 3 is a schematic, cross-sectional view demonstrating
another embodiment of this invention;
[0016] FIG. 4 is a schematic, cross-sectional view illustrating yet
another embodiment of this invention;
[0017] FIG. 5 is a schematic, cross-sectional view illustrating yet
another embodiment of this invention; and
[0018] FIG. 6 is a schematic, planar view of an integrated circuit
chip with a double seal ring structure in accordance with another
preferred embodiment of this invention.
DETAILED DESCRIPTION
[0019] The present invention pertains to a seal ring structure for
an integrated circuit chip. The number of seal ring(s) in the seal
ring structure depends on requirements and is not limited to what
is illustrated in the embodiments. If there is an outer seal ring,
it may be a continuous ring, while an inner seal ring may be
divided into at least two portions including a conductive rampart
that is situated in front of a sensitive analog and/or RF circuit
block of the integrated circuit chip.
[0020] A deep N well under the conductive rampart may shield the
analog and/or RF circuit from noise, which, for example, propagates
through the outer seal ring, thereby reducing the noise-coupling
effects. The continuous outer seal ring keeps the moisture and
corrosive substances from entering the IC.
[0021] Please refer to FIG. 1 and FIG. 2. FIG. 1 is a schematic,
planar view of an integrated circuit chip 10 with a double seal
ring structure 12 in accordance with one embodiment of this
invention. FIG. 2 is a schematic, cross-sectional view taken along
line I-I' of FIG. 1. As shown in FIG. 1, the integrated circuit
chip 10 comprises at least one analog and/or RF circuit block 14, a
digital circuit 16 and a double seal ring structure 12 surrounding
and protecting the analog and/or RF circuit block 14 and digital
circuit 16.
[0022] The integrated circuit chip 10 further comprises a plurality
of input/output (I/O) pads 20. As previously described, noises such
as those originated from a digital power V.sub.DD signal line or a
signal output pad 20a of the digital circuit 16 can propagates
through the seal ring and adversely affects the performance of the
sensitive analog and/or RF circuit 14. The noise propagation path
30 is specifically indicated in FIG. 1. The present invention aims
to tackle this problem.
[0023] According to the present invention, the double seal ring
structure 12, which is disposed along the periphery of the chip,
includes a continuous outer seal ring 122 and a discontinuous inner
seal ring 124. Though a double seal ring structure 12 is shown in
this embodiment, the number of seal ring(s) in the seal ring
structure depends on requirements and is not limited to what is
illustrated herein. Besides, though the outer seal ring 122 is
continuous and the inner seal ring 124 is discontinuous in this
embodiment, the outer one could be either continuous or
discontinuous, and the inner one could be either continuous or
discontinuous as well. The inner seal ring 124 is divided into at
least two portions including a first portion 124a and a second
portion 124b spaced apart from the first portion 124a. Between the
first portion 124a and the second portion 124b, there is provided a
chipped region 125.
[0024] As shown in FIG. 2, the first portion 124a and the second
portion 124b are different from each other mainly underneath the
main surface 100a of the P substrate 100. The first portion 124a
comprises a conductive rampart 201 that is made of a stack of metal
layers such as M1 and M2 and contact/via layers such as C and V1
and is manufactured step by step as sequential depositions of
insulators and metals in conjunction together with the fabrication
of the integrated circuit elements. The first portion 124a further
comprises a P.sup.+ region 202 situated under the conductive
rampart 201. There may be a P well (not shown) under the P.sup.+
region 202.
[0025] The second portion 124b is positioned facing the analog
and/or RF circuit block 14 for shielding the noise propagating
through the continuous outer seal ring 122. Preferably, the length
of the second portion 124b is equal to or greater than the span of
the shielded analog and/or RF circuit block 14. Above the main
surface 100a of the P substrate 100, likewise, the second portion
124b comprises a conductive rampart 301 that is made of a stack of
metal layers such as M1 and M2 and contact/via layers such as C and
V1 and is manufactured step by step as sequential depositions of
insulators and metals in conjunction together with the fabrication
of the integrated circuit elements.
[0026] The present invention features the seal ring structure
underneath the main surface 100a of the P substrate 100. Under the
conductive rampart 301, the second portion 124b further comprises a
P.sup.+ region 302, a first N well 304a electrically isolated from
the P.sup.+ region 302 by a first shallow trench isolation (STI)
structure 360a, a second N well 304b electrically isolated from the
P.sup.+ region 302 by a second STI structure 360b, and a deep N
well 310, wherein the P.sup.+ region 302, the first N well 304a,
the second N well 304b, the first and second STI structures 360a
and 360b are formed on/over the deep N well 310. The first and
second N wells 304a and 304b are electrically isolated from the
P.sup.+ region 202 by an STI structure 260.
[0027] According to the preferred embodiment, the first and second
N wells 304a and 304b have a junction depth d.sub.1 of about
11000-15000 angstroms and the deep N well 310 has a junction depth
d.sub.2 of about 19000-21000 angstroms. The deep N well 310 may be
grounded or coupled to a supply voltage, such as V.sub.DD. It is
advantageous to use the present invention because the deep N well
310 situated under the second portion 124b can reduce the substrate
noise coupling.
[0028] FIG. 3 is a schematic, cross-sectional view demonstrating
another embodiment of this invention. As shown in FIG. 3, likewise,
under the conductive rampart 301, the second portion 124b comprises
a P.sup.+ region 302, a first N well 304a electrically isolated
from the P.sup.+ region 302 by a first STI structure 360a, a second
N well 304b electrically isolated from the P.sup.+ region 302 by a
second STI structure 360b, and a deep N well 310, wherein the
P.sup.+ region 302, the first N well 304a, the second N well 304b,
the first and second STI structures 360a and 360b are formed
on/over the deep N well 310. The first and second N wells 304a and
304b are electrically isolated from the P.sup.+ region 202 by an
STI structure 260. In addition, a P well 324 is provided between
the P.sup.+ region 302 and the deep N well 310. The second portion
124b further comprises N.sup.+ regions 402a and 402b.
[0029] FIG. 4 is a schematic, cross-sectional view illustrating yet
another embodiment of this invention. As shown in FIG. 4, under the
conductive rampart 201 of the first portion 124a of the inner seal
ring 124, a deep N well 210 is provided under the P.sup.+ region
202. Under the conductive rampart 301 of the second portion 124b of
the inner seal ring 124, merely a P.sup.+ region 302 and a deep N
well 310 are provided. The STI structures 360a and 360b and the
first and second N wells 304a and 304b in FIG. 2 are omitted.
[0030] FIG. 5 is a schematic, cross-sectional view illustrating yet
another embodiment of this invention. As shown in FIG. 5, likewise,
under the conductive rampart 201 of the first portion 124a of the
inner seal ring 124, a deep N well 210 is provided under the
P.sup.+ region 202. Under the conductive rampart 301 of the second
portion 124b of the inner seal ring 124, a P.sup.+ region 302, a P
well 324 and a deep N well 310 are provided. The STI structures
360a and 360b and the first and second N wells 304a and 304b in
FIG. 2 are omitted.
[0031] FIG. 6 is a schematic, planar view of an integrated circuit
chip 10a with a double seal ring structure 12 in accordance with
another preferred embodiment of this invention, wherein like
numeral numbers designate like regions, layers or elements. As
shown in FIG. 6, likewise, the integrated circuit chip 10a
comprises at least one analog and/or RF circuit block 14, a digital
circuit 16 and a double seal ring structure 12 surrounding and
protecting the analog and/or RF circuit block 14 and digital
circuit 16. The integrated circuit chip 10a further comprises a
plurality of I/O pads 20. Noises such as those originated from a
digital power V.sub.DD signal line or a signal output pad 20a of
the digital circuit 16 propagates through the seal ring and
adversely affects the performance of the sensitive analog and/or RF
circuit block 14.
[0032] The double seal ring structure 12 includes a continuous
outer seal ring 122 and a discontinuous inner seal ring 124. Though
a double seal ring structure 12 is shown in this embodiment, the
number of seal ring(s) in the seal ring structure depends on
requirements and is not limited to what is illustrated herein.
Besides, though the outer seal ring 122 is continuous and the inner
seal ring 124 is discontinuous in this embodiment, the outer one
could be either continuous or discontinuous, and the inner one
could be either continuous or discontinuous as well. The inner seal
ring 124 is divided into two portions including a first portion
124a and a second portion 124b. The second portion 124b serves to
shield the noise propagating through the outer seal ring 122.
Preferably, the length of the second portion 124b is equal to or
greater than the span of the shielded analog and/or RF circuit
block 14.
[0033] The ring structure of the second portion 124b is similar to
that as set forth in FIG. 2 or FIG. 3. According to this invention,
the second portion 124b may be coupled to an independent ground or
an independent supply voltage. According to this invention, the
second portion 124b may be coupled to the independent ground
through an independent pad and an interconnection trace. The term
"independent" used herein means that the ground, pad or supply
voltage is not commonly used by the analog circuit, RF circuit or
digital circuit.
[0034] In this embodiment, the second portion 124b may be coupled
to an independent pad 20b through an interconnection trace 124c.
The interconnection trace 124c may be comprised of a topmost metal
layer of the integrated circuit chip 10a and an aluminum layer (not
shown). By doing this, the second portion 124b could be coupled to
an independent ground (not shown) or an independent supply voltage,
such as V.sub.SS, and the noise coupling can be significantly
reduced.
[0035] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention. Accordingly, the
above disclosure should be construed as limited only by the metes
and bounds of the appended claims.
* * * * *